A variety of expansion joint assemblies have been developed. Generally speaking, such assemblies have involved use of expandable membranes which form an upper exposed surface at or near a flush relationship with the adjacent floor. In response to relative movement of the structural members, which may be due to changes in the ambient temperature, the membrane will expand and contract. The side edges of the membrane are attached to the structural members to achieve this result. Beneath the membranes there are provided relatively movable support means for the membranes since they are wide and do not have sufficient strength to support pedestrians and other traffic.
The support means have taken the form of metal plates and other components. Such means often require considerable blockout depth relative to the floor surface. In addition, the designs of the prior art have limited versatility and are therefore often not usable where complex tread-riser directional changes need to be accommodated. Furthermore, such systems often encounter problems with bonding between the structural members and system components due to differences in the coefficient of thermal expansion.